-- 控制结构 if-else
-- 单个 if 分支
x = 10
if x > 0 then
  print("x is a positive number")
end


-- 两个分支 if-else
if x > 0 then
  print("x is a position number")
else
  print("x is non-positive number")
end

-- 多个分支 if-elseif-else

score = 0
if score == 100 then
  print("very good! your score is 100")
elseif score >=60 then
  print("Congratulations, you have passed it,your score greater or equal to 60")
else
  if score > 0 then
    print("yout score is better that 0")
  else
    print("my god, your score turned out to be 0")
  end
end
